1. Field of the Invention
The present invention relates to natural language understanding systems, and more particularly to a method and system for building a natural language understanding system with hierarchical translation of commands to improve speed and accuracy of translations.
2. Description of the Related Art
State-of-the-art natural language understanding systems typically perform a direct translation of the user input to a formal command in a single step. However, when the number of formal commands is large, a large number of features may be required to perform a direct one-step translation. Increasing the number of features introduces additional statistical noise that results in a degradation of accuracy of the system. Additional computational difficulties include added computation time and memory, and possible numerical instability due to the large number of features. Consider for example translating commands such as "forward this message" (action), "how do I forward a message" (help), or "did I forward a message" (query). All three of these sentences are related to forwarding a message, and as such the key word "forward" may appear to be important, but a feature set including the word "forward" would only introduce noise and lead to inaccuracies in the translation.
Therefore, a need exists for a system and method for reducing a number of features needed to translate a command in a natural language understanding system. A further need exists for a hierarchical translation method and system for translating command in a faster and more accurate manner.